INTERNAL BIAS EFFECTS ON PYROELECTRIC MEASUREMENTS NEAR CURIE-TEMPERATURE IN TRIGLYCINE SULFATE

Simultaneous measurements of the pyroelectric (PR) coefficient lambda and permittivity epsilon from the PE voltage responses to step ir radiation signals in triglycine sulphate (TGS) are reported as functions of temperature in both the ferroelectric and paraelectric phases. It is shown that the observed lowering and widening of the peaks of lambda and epsilon , the appearance of a PE effect in the paraelectric phase, and the shift of the epsilon peak to temperatures above T//c can be explained by the existence of an internal bias field E//b. The values of E//b calculated to fit the experimental results vary in different TGS samples from 30 to 150 V/cm.